Highly conductive porous paper-based metal thin films

Abstract

A porous conductive thin film includes a layer of metal nanoparticles decorated on a layer of conductive carbon nanomaterials. The thin film can be supported by a porous support. The porous support can be a MCE paper upon which a metallic or semi-metallic single-walled carbon nanotube (SWCNT) layer is decorated with gold nanoparticles (AuNPs) or platinum nanoparticles (PtNPs). The thin film can be constructed by filtering a dispersion of SWCNTs onto MCE filter paper followed by the filtration of a citrate stabilized dispersion of AuNPs or PtNPs onto the SWCNT layer.

We claim: 
     
       1. A porous conductive thin film, comprising a filter medium support, at least one first layer comprising a plurality of conductive carbon nanomaterials with an aspect ratio in excess of 100, and at least one second layer consisting of a continuous network of spherical or rod shaped metal nanoparticles having an aspect ratio of 1.4 to 18 and 2 nm to 100 nm in size. 
     
     
       2. The porous conductive thin film according to  claim 1 , wherein the conductive carbon nanomaterials comprise graphene flakes, multi-walled carbon nanotubes, metallic or semi-metallic single-walled carbon nanotubes, or any mixture thereof. 
     
     
       3. The porous conductive thin film according to  claim 1 , wherein the metal nanoparticles are amorphous metal nanoparticles. 
     
     
       4. The porous conductive thin film according to  claim 1 , wherein the metal nanoparticles comprise gold, silver, copper, platinum, palladium, any alloy thereof, or mixtures thereof. 
     
     
       5. The porous conductive thin film according to  claim 1 , wherein the filter medium is a MCE, PVDF, PES PTFE, polycarbonate, or cellulose filter. 
     
     
       6. The porous conductive thin film according to  claim 1 , comprising a multiplicity of layers wherein the layers of conductive carbon nanomaterials alternate with layers of metal nanoparticles. 
     
     
       7. The porous conductive thin film according to  claim 6 , wherein the layers of metal nanoparticles comprise different metals. 
     
     
       8. The porous conductive thin film according to  claim 1 , wherein the metal nanoparticles are about 2 to about 100 nm in diameter. 
     
     
       9. The porous conductive thin film according to  claim 1 , wherein the metal nanoparticles are spherical or rod-like. 
     
     
       10. A method of forming a porous conductive thin film according to  claim 1 , comprising:
 providing a filter medium support; 
 providing a first aqueous dispersion of conductive carbon nanomaterials; 
 providing a first aqueous dispersion of spherical or rod shaped metal nanoparticles having an aspect ratio of 1.4 to 18 and 2 nm to 100 nm in size; 
 filtering the first aqueous dispersion of the conductive carbon nanomaterials through the filter medium support to form a first layer of conductive carbon nanomaterials; and 
 filtering the first aqueous dispersion of the metal nanoparticles through the first layer of conductive carbon nanomaterials and the filter medium support to form a second layer comprising metal nanoparticles. 
 
     
     
       11. The method according to  claim 10 , further comprising filtering a second aqueous dispersion of the conductive carbon nanomaterials through the second layer of metal nanoparticles and the filter medium support to form a third layer of conductive carbon nanomaterials and filtering a second aqueous dispersion of the metal nanoparticles through the third layer of conductive carbon nanoparticles, the second layer of metal nanoparticles and the filter medium support to form a fourth layer of metal particles. 
     
     
       12. The method according to  claim 10 , further comprising alternating steps of filtering an n-th aqueous dispersion of conductive carbon nanomaterials and an m-th aqueous dispersion of metal nanoparticles to form a (2n−1) th layer of conductive carbon nanomaterials alternating with a 2m th layer of metal nanoparticles, wherein n is 3 to 10. 
     
     
       13. The method according to  claim 10 , wherein the conductive carbon nanomaterials are metallic or semi-metallic single-walled carbon nanotubes and the metal nanoparticles are gold nanoparticles or platinum nanoparticles. 
     
     
       14. The method according to  claim 10 , wherein the dispersion of the metal nanoparticles is a citrate stabilized gold nanoparticle dispersion. 
     
     
       15. An electronic device, comprising a porous conductive thin film according to  claim 1 . 
     
     
       16. The electronic device according to  claim 15 , wherein the porous conductive thin film is an electrode. 
     
     
       17. The electronic device according to  claim 15 , wherein the porous conductive thin film is a structure in a detector, a transistor, or a photovoltaic device.